1. Field of the Invention
The present invention relates generally to the field of inhalation devices, and more specifically, to inhalation devices that utilize vibration to facilitate suspension of powder (e.g., powdered medication) into an inhaled gas stream (e.g., of inhaled air). Particular utility for the present invention is found in the area of facilitating inhalation of powdered medications (e.g., bacterial vaccines, sinusitis vaccines, antihistaminic agents, vasoconstricting agents, anti-bacterial agents, anti-asthmatic agents, theophylline, aminophylline, di-sodium cromolyn, etc.), although other utilities are contemplated, including other medicament applications.
2. Brief Description of Related Prior Art
Certain diseases of the respiratory tract are known to respond to treatment by the direct application of therapeutic agents. As these agents are most readily available in dry powdered form, their application is most conveniently accomplished by inhaling the powdered material through the nose or mouth. This powdered form results in the better utilization of the medicament in that the drug is deposited exactly at the site desired and where its action may be required; hence, very minute doses of the drug are often equally as efficacious as larger doses administered by other means, with a consequent marked reduction in the incidence of undesired side effects and medicament cost. Alternatively, the drug in this form may be used for treatment of diseases other than those of the respiratory system. When the drug is deposited on the very large surface areas of the respiratory tract, it may be very rapidly absorbed into the blood stream; hence, this method of application may take the place of administration by injection, tablet, or other conventional means.
Several inhalation devices useful for dispensing this powder form of medicament are known in the prior art. For example, in U.S. Pat. Nos. 3,507,277; 3,518,992; 3,635,219; 3,795,244; and 3,807,400, inhalation devices are disclosed having means for piercing of a capsule containing a powdered medicament, which upon inhalation is drawn out of the pierced capsule and into the user's mouth. Several of these patents disclose propeller means, which upon inhalation aid in dispensing the powder out of the capsule, so that it is not necessary to rely solely on the inhaled air to suction powder from the capsule. For example, in U.S. Pat. No. 2,517,482, issued to Hall, a device is disclosed having a powder containing capsule placed in a lower chamber before inhalation, where it is pierced by manual depression of a piercing pin by the user. After piercing, inhalation is begun and the capsule is drawn into an upper chamber of the device where it moves about in all directions to cause a dispensing of powder through the pierced holes and into the inhaled air stream. U.S. Pat. No. 3,831,606 discloses an inhalation device having multiple piercing pins, propeller means, and a self-contained power source for operating the propeller means via external manual manipulation, so that upon inhalation the dispensing the powder into the stream of inhaled air. See also U.S. Pat. No. 5,458,135.
These prior art devices present several problems and posesses several disadvantages which are remedied by the inhalation devices of the present invention. For instance, these prior art devices require that the user exert extreme effort in inhalation to effect dispensing or withdrawal of powder from a pierced capsule into the inhaled air stream. With these prior art devices, suction of powder through the pierced holes in the capsule caused by inhalation generally does not withdraw all or even most of the powder out of the capsule, thus causing a waste of the medicament. Another most important problem which has not been solved by the prior art devices is the presence of uncontrolled amounts or clumps of powdered material being inhaled into the user's mouth, rather than a constant inhalation of controlled amounts of finely dispersed powder.
The above description of the prior art is taken largely from U.S. Pat. No. 3,948,264 to Wilke et al, who disclose a device for facilitating inhalation of a powdered medication that includes a body portion having primary and secondary air inlet channels and an outlet channel. The secondary inlet channel provides an enclosure for a capsule containing the powdered medication and the outlet channel is formed as a mouthpiece protruding from the body. A capsule piercing structure is provided, which upon rotation puts one or more holes in the capsule so that upon vibration of the capsule by an electromechanical vibrator, the powdered drug may be released from the capsule. The piercing means disclosed in Wilke et al includes three radially mounted, spring-biased piercing needles mounted in a trochoidal chamber. Upon hand rotation of the chamber, simultaneous inward radial motion of the needles pierces the capsule. Further rotation of the chamber allows the needles to be retracted by their spring mountings to their original positions to withdraw the needles from the capsule. The electromechanical vibrator includes, at its innermost end, a vibrating plunger rod which projects into the intersection of the inlet channel and the outlet channel. Connected to the plunger rod is a mechanical solenoid buzzer for energizing the rod to vibrate. The buzzer is powered by a high energy electric cell and is activated by an external button switch. According to Wilke et al, upon inhalation through outlet channel 3 and concurrent pressing of switch 10d to activate the electromechanical vibrating means 10, air is sucked through inlet channels 4 and 12 and the air stream through the secondary inlet channel 4 raises the capsule up against the vibrating plunger rod 10a. The capsule is thus vibrated rapidly with powder being fluidized and dispensed from the pierced holes therein. The air stream through inlet channel 4 and 12 aids in withdrawal of powder from the capsule and carries this powder through the outlet channel 3 to the mouth of the user." (Wilke et al, column 3, lines 45-55). Wilke et al further discloses that the electromechanical vibrator means may be placed at a right angle to the inlet chamber and that the amplitude and frequency of vibration may be altered to regulate dispensing characteristics of the inhaler.
Thus, as noted above, the vibrator in Wilke et al.'s disclosed inhaler is an electromechanical device consisting of a rod driven by a solenoid buzzer. A disadvantage of electromechanical vibrators of the type disclosed in Wilke et al. is that they include a relatively large number of mechanical moving parts that can be subject to significant wear and tear. Thus, disadvantageously, the inhaler disclosed in Wilke et al. requires frequent maintenance (e.g., to replace the mechanical moving parts that are subject to wear and tear).
Further disadvantageously, although Wilke et al. discloses that the amplitude and frequency of vibration may be varied in Wilke et al.'s disclosed inhaler in order to regulate dispensing characteristics of the inhaler, no means is provided in Wilke et al.'s disclosed inhaler to permit optimal adjustment of such vibration characteristics without disassembly of the inhaler and modification of the vibrator so as to vibrate at a different frequency and/or amplitude. Additionally, Wilke et al. nowhere discloses which amplitudes and frequencies of vibration are optimal for dispensing various types of powdered medications.
Moreover, as noted above, in Wilke et al.'s disclosed device, vibration of the powder is activated by depressing a push button. This can be difficult and painful for some users (e.g., patients suffering from extreme arthritis).
Finally, in order to use Wilke et al.'s disclosed inhaler most efficaciously, the user must depress the vibration-actuating push button at precisely the same time that the user begins inhalation. This can also be difficult for some users (e.g., very young patients, patients suffering from neuromuscular disorders, etc.).